This invention relates to rotary piston engines, and particularly to an improved rotary piston engine in which two inner wall of a casing are of circular cross section about respective spacedly parallel axes and intersect each other to define respective, communicating cavities, two rotary pistons being mounted in the cavities for simultaneous rotation about the axes in opposite respective directions.
A Roots blower is typical of the prior art with the improvement of which this invention is concerned. Each rotor or rotary piston of a Roots blower has at least one first sector and at least one second sector angularly offset from the first sector and of smaller radius. The radially outer circumferential portions of the sectors jointly constitute the circumference of the rotor which extends in a closed loop about the axis of rotation and engages the circumference of the other rotor in all angular rotor positions. During simultaneous rotation of the rotors, the circumferential portion of each first sector sealingly engages the casing wall, and each second sector and the associated wall radially bound a working chamber. The engaged circumferences of the two rotors are virtually sealed to each other. Ports in the casing supply a fluid to be blown and release the conveyed fluid. Roots blowers are commonly employed for conveying gases and liquids, and it has been suggested that they be modified to operate as internal combustion engines. The modified blowers, however, have been found ineffective because they cannot sealingly contain combustion gases under high pressures for a period sufficient to permit the energy stored in the hot gases to be converted to mechanical power.